Infectious Mononucleosis
A viral infection famous for causing severe fatigue, sore throat, and swollen lymph nodes, often called the 'kissing disease'.
Emergency Management: Impending airway closure requires emergent IV Corticosteroids and ENT consultation. Splenic rupture presents with acute hemorrhagic shock, requiring massive transfusion and immediate surgical intervention.
Infectious Mononucleosis is an acute viral syndrome characterized by fever, pharyngitis, and prominent lymphadenopathy, primarily caused by the Epstein-Barr Virus (EBV).
Detailed Overview
EBV is a human herpesvirus (HHV-4) transmitted primarily through infected saliva. It infects B lymphocytes and epithelial cells of the oropharynx. The profound immune response, characterized by the proliferation of atypical cytotoxic T cells (CD8+), causes the prominent systemic symptoms. It commonly affects adolescents and young adults.
Epidemiology & Demographics
Peak incidence is between 15 and 24 years of age. By adulthood, over 90% of the worldwide population is seropositive for EBV. Incidence in the US is roughly 500 cases per 100,000 persons per year.
Etiological Mechanism
Epstein-Barr virus (EBV) causes 90% of cases. Cytomegalovirus (CMV), Toxoplasma gondii, and primary HIV infection can cause a 'mononucleosis-like' syndrome.
Primary Causes
Epstein-Barr Virus (EBV)
EBV enters via the oropharynx and binds to the CD21 receptor on B lymphocytes. The virus replicates within these cells and causes a lifelong latent infection. The body mounts a massive cellular immune response, particularly via CD8+ cytotoxic T cells, which appear as 'atypical lymphocytes' on a peripheral smear. This rapid expansion of T cells infiltrates lymphoid tissues, causing massive tonsillar enlargement, generalized lymphadenopathy, and splenomegaly.
Diagnostic Criteria & Guidelines
Clinical triad of fever, pharyngitis, and lymphadenopathy, confirmed by a positive heterophile antibody test (Monospot) and peripheral smear showing lymphocytosis with >10% atypical lymphocytes.
Supportive care is the mainstay. 1. Hydration and rest. 2. Analgesics/Antipyretics: Acetaminophen 500-1000 mg PO Q6H or Ibuprofen 400 mg PO Q6H for throat pain and fever. Avoid strenuous activity to prevent splenic rupture.
Second-Line & Adjunctive Therapy
Corticosteroids (e.g., Dexamethasone 10 mg IV or Prednisone 40 mg PO taper) are strictly reserved for impending airway obstruction, massive splenomegaly, or severe hemolytic anemia.
Surgical & Procedural Management
Emergency splenectomy is required for splenic rupture. Tonsillectomy is rarely needed for recalcitrant airway obstruction.
Patient Counseling & Advice
Reassure that prolonged fatigue (up to 3-6 months) is a normal part of the recovery process. Warn about the signs of splenic rupture (sudden, severe left upper quadrant pain radiating to the left shoulder - Kehr's sign).
Follow-Up & Monitoring Schedule
Outpatient follow-up in 1-2 weeks to assess spleen size and airway. Clear for contact sports usually requires a physical exam confirming resolution of splenomegaly at week 4.
Preventive Strategies
No vaccine exists. Avoid sharing drinks, utensils, and kissing when actively ill, though asymptomatic shedding can occur intermittently for life.
Generally excellent with full recovery. Fatigue is the most persistent symptom. EBV remains latent for life and is weakly associated with future risk of Hodgkin lymphoma, Burkitt lymphoma, and Multiple Sclerosis.